On Fusion energy

Along with fission, fusion constitutes nuclear energy. Fusion is a form of power generation that generates electricity by using nuclear fusion reaction. In fusion, two atomic nuclei combine to form a heavier nucleus, while releasing energy. Devices that produce energy in this way are known as fusion reactors.

A very complex fusion reactor

History of fusion:

1920–1930: Learning about the stars and matter:

Robert d’Escourt Atkinson and Fritz Houtermans provided the first calculations of the rate of nuclear fusion in stars. And at the same time, Ernest Rutherford was exploring the structure of the atom. With his famous 1934 experiment, Rutherford showed the fusion of deuterium into helium, and observed that “an enormous effect was produced” during the process. His student Mark Oliphant used an updated version of the equipment, firing deuterium rather than hydrogen and discovered helium-3 and tritium, showing that heavy hydrogen nuclei could be made to react with each other. This was the first direct demonstration of fusion in the lab. This understanding of nuclear fusion was tied together by Hans Bethe’s work on stellar nucleosynthesis where he described that it is through proton-proton chain reactions that the Sun and stars release energy.

1950s: Harnessing fusion on earth:

By the 1950s, researchers started looking at possibilities of replicating the process of nuclear fusion on Earth. And in 1950 soviet scientists Andrei Sakharov and Igor Tamm proposed the design for a type of magnetic confinement fusion device, the tokamak. This was followed, in 1951, by Lyman Spitzer’s concept for the stellarator. The stellarator concept dominated fusion research throughout the 1950s but lost its sway when the experimental research on tokamak systems by Soviet scientist Lev Artsimovich showed that the tokamak was a more efficient concept.

1970–1980: Design on JET and starting for ITER:

By the 1970s it was clear that attaining fusion energy would be one of science’s greatest challenges and collaboration might be key to meeting the challenge. European countries came together and began design work on the Joint European Torus, JET, in 1973. In 1977, the European commission gave the green signal for the project and Culham in Oxford, UK, was selected as the site for JET. The construction of JET, which would become the largest operational magnetic confinement plasma physics experiment, was completed on time and on budget in 1983 and the first plasmas were achieved.

The 80’s also saw the iron curtain being lifted slightly when ITER was set in motion at the Geneva Superpower Summit in November 1985. The idea of a collaborative international project to develop fusion energy for peaceful purposes was proposed by General Secretary Gorbachev of the former Soviet Union to US President Reagan.

1990–2000s: JET record and a home for ITER:

The first experiments using tritium was carried out in JET, making it the first reactor in the world to run on the fuel of a 50–50 mix of tritium and deuterium. In 1997, using this fuel, JET set the current world record for fusion output at 16 MW from an input of 24 MW of heating. This is also the world record for Q, at 0.67. A Q of 1 is breakeven, and to achieve fusion energy the Q value must be greater than 1. The aim of ITER is to achieve a Q of 10. In 2005, the ITER Members unanimously agreed that ITER would be built in Cadarache in France. In November 2017, the ITER project passed the 50 percent milestone of work scope completed to first plasma.

How fusion works:

In a fusion reaction, two light nuclei merge to form a single heavier nucleus. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy. This is in accordance to Einstein's famous equation.

And because the speed of light is a very large number the energy produced will also be very large.

Where fusion is being researched:

Because Fusion offers the potential of almost infinite energy not just for the present but also for future generations, many countries are investing in fusion research. The main challenge today is to achieve rate of heat emitted by a fusion plasma that exceeds the rate of energy injected into the plasma.

Places of research include the Joint European Torus (JET), Mega Amp Spherical Tokamak (MAST), and the tokamak fusion test reactor (TFTR) at Princeton in the USA. The ITER (International Thermonuclear Experimental Reactor) project currently under construction in Cadarache, France will be the largest tokamak when it operates in the 2020s. The Chinese Fusion Engineering Test Reactor (CFETR) is a tokamak which is reported to be larger than ITER, and due for completion in 2030. Meanwhile it is running its Experimental Advanced Superconducting Tokamak (EAST). In the UK, Tokamak Energy has commissioned and is further developing its ST40 tokamak.

Advantages:

1. A lot of energy — fusion energy released millions of times more energy than released by burning of coal and fossil fuels. This results in the potential to provide the kind of baseload energy needed to provide electricity to our cities and our industries.
2. Sustainability: Fusion fuels are widely available and nearly inexhaustible. Deuterium can be distilled from all forms of water, while tritium will be produced during the fusion reaction as fusion neutrons interact with lithium. (Terrestrial reserves of lithium would permit the operation of fusion power plants for more than 1,000 years, while sea-based reserves of lithium would fulfil needs for millions of years.)
3. No carbon dioxide: Fusion doesn’t emit harmful toxins like carbon dioxide or other greenhouse gases into the atmosphere. Its major by-product is helium: an inert, non-toxic gas.
4. No long lived radioactive waste — Nuclear fusion reactors produce no high activity, long-lived nuclear waste. The activation of components in a fusion reactor is low enough for the materials to be recycled or reused within 100 years.
5. Limited risk of proliferation — Fusion doesn’t employ fissile materials like uranium and plutonium. (Radioactive tritium is neither a fissile nor a fissionable material.) There are no enriched materials in a fusion reactor like ITER that could be exploited to make nuclear weapons.
6. No risk of meltdown — A Fukushima-type nuclear accident is not possible in a tokamak fusion device. It is difficult enough to reach and maintain the precise conditions necessary for fusion — if any disturbance occurs, the plasma cools within seconds and the reaction stops. The quantity of fuel present in the vessel at any one time is enough for a few seconds only and there is no risk of a chain reaction.
7. Cost — The power output of the kind of fusion reactor that is envisaged for the second half of this century will be similar to that of a fission reactor, (i.e., between 1 and 1.7 gigawatts). The average cost per kilowatt of electricity is also expected to be similar … slightly more expensive at the beginning, when the technology is new, and less expensive as economies of scale bring the costs down.

Disadvantages:

There exists only one real disadvantage of fusion energy and that is the difficulty of achieving it.

In the sun and stars, high temperatures and powerful gravitational forces naturally prepare a fusion environment. But here on our planet, we face the challenge of making nuclear fuel hot and enough limitations to begin a self-sustaining ignition.

Just think about trying to hold the plasma (a mixture of gaseous deuterium, tritium ions and atoms, and the helium fusion product) at millions of degrees celsius. Scientists couldn’t find materials that can withstand these temperatures. Therefore, scientists try to keep the plasma in a magnetic field provided by superconducting magnets around the fusion vessel/chamber. This method is tough to achieve compared to nuclear fission.

General opinion:

I truly believe that fusion energy is the future of power generation and that it can be used to fuel literally everything from cars to entire cities. It does not require any specific fuel like other forms of energy. It is completely reliable and safe. Our technology is not advanced enough to harness but I believe that governments and private companies should spend more money on its research and development due to its enormous potential.